To enable sharing of data among computer users, most computer systems in use today are interconnected via a computer network. Computers in an office, for example, may be connected over a local area network (LAN) to gain access to a server computer, which manages common data storage. As used herein, a server refers to a computer that services and manages requests for data and other files from network computers utilizing wired and wireless communication networks. In the case of an Internet server, the computer network is the Internet. The Internet is a global computer network in which literally millions of user computers communicate with server computers over a widely distributed network.
The number of people using the Internet has been growing at a very fast rate, while the services provided over the Internet are increasingly becoming mission critical. One such mission critical service can be found in the growth of cloud computing services. Cloud computing provides computation, software, data access, and storage services that do not require end-user knowledge of the physical location and configuration of the system that delivers the services. Parallels to this concept can be drawn with the electricity grid, wherein end-users consume power without needing to understand the component devices or infrastructure required to provide the service.
Hence, enabling high performance, reliability, availability, and scalability as well as the creation of management tools, have become key issues in the development and maintenance of Internet servers that provide services such as cloud computing. The current approach for handling these issues from the server perspective is based on the concept of load balancing. The key to the load balancing approach is the ability to handle the various network requests with a system called a load balancer. A load balancer is a hardware device similar to a network router, a network gateway, a switch router or a server computer executing load balancing software that allows it to act as a primary network address dispatcher between various network resources.
Load balancing is not the only concern for network access in an Internet or cloud computing environment. Cloud resources could reside on-premise at a client site or off-premise at a service provider location. Cloud computing can take the form of public clouds, private clouds, inter-clouds, or Hybrid Clouds. In a cloud-computing environment, a client computer may be a mobile device accessing an application on a cloud server computer via a default network gateway during a road trip from New York, N.Y. to Washington, D.C. Between New York and Philadelphia, Pa. the default network gateway may be adequate as because it is geographically local to the mobile device. However, the further away the mobile device moves from New York City the server computers in New York may become less relevant to a user application that needs up-to-the-minute local information. For, example, the user application may require current traffic conditions for logistical purposes. If the mobile device is still connecting to a default gateway in New York as it passes through Philadelphia, the user's access to the most up-to-the-minute data may slowed by this connection. Furthermore, the application would have to be restarted if it was handed off to another more local gateway. Therefore, it would be desirable if in there were a method to dynamically migrate the client computer's connection from the distant default network gateway to a local default network gateway without losing the connection.
The default network gateways are also often a single point of failure in the case where there is no stand-by network gateway available. When there is a stand-by network gateway and a default network gateway failure occurs, the long reconfiguration time of the stand-by network gateway can severely affect the quality of service for network users. Finally, conventional load balancing systems do not typically maintain the network connection between client machines and servers during migration to a VIP address or in the event of a server failure. This can require client machines to repeat their requests for data, thereby reopening the network connection. All of these situations result in slowed responses or complete failures in response to network requests for Web pages, applications and other data.